build-deftly

This crate is a project to test the derive-deftly macro system by attempting to clone the derive_builder crate.

As it stands, I think I have gotten an implementation for every feature that derive_builder has, but in some cases I had to give them a different syntax. I have not tested every combination of features; probably some combinations will break.

Converting to use this crate.

Instead of this...

use derive_builder::Builder;
#[derive(Builder)]
struct MyStruct {
   ...
}

Say this:

use derive_deftly::Deftly;
use build_deftly::templates::*;
#[derive(Deftly)]
#[derive_deftly(Builder)]

If you use any #[builder(...)] options, you will have to change them to #[deftly(builder(...))] instead.

Some options have a different form; see below.

Supported options

So far, these options are supported. (Remember, they go inside #[deftly(builder(...))].)

• pattern = "PAT" — Supported on fields and structs. PAT can be immutable, owned, or mutable (the default).

• setter(skip), setter(custom) — Supported on fields and structs. Note that we do not support skip=true, skip=false, custom=true, or custom=false. Instead of skip=true, say skip. Instead of custom=true, say custom. Instead of skip=false or custom=false, say "enabled", as in setter(enabled). (See derive-deftly#40, derive-deftly#48, derive-deftly#49.)

• vis = "VISIBILITY" — Supported on fields and structs. By default, builders and setters have the same visibility as the original struct. To override this on the builder and its methods, say (for example) vis="pub" or vis="pub(crate). This replaces derive_builder's public and private options.

• name = "NAME" — Supported on structs. Renames the generated builder structure and error enum.

• setter(prefix = "PREFIX") — Supported on fields and structs. Adds a prefix (with an underscore) to setter methods.

• setter(name = "PREFIX") — Supported on fields. Rename a single setter method.

• setter(into) — Supported on fields. Makes a setter generic over V:Into<..>.

• setter(try_into) — Supported on fields. Makes a setter generic over V:TryInto<..>.

• setter(try_into) — Supported on fields of type Option<T>. Makes a setter take a T instead of an Option<T>. (When used with into, makes the setter take impl Into<T> instead of impl Into<Option<T>>; behaves analogously with try_into.)

• default, default_val = "EXPR" — Supported on fields. Unlike derive_builder, these are separate options, since derive_deftly doesn't support options with optional values. (See see derive-deftly#40, derive-deftly#48.)

• build_fn(skip) — Supported on structs. Skips generation of the build() function.

• build_fn(name = "NAME") — Supported on structs. Provides a new name for the build() function.

• build_fn(validate = "PATH") — Supported on structs. Provides a function to run before the rest of the builder, to validate its inputs. The function must take the Builder by reference, and return Result<_, String>.

• build_fn(error = "NAME") — Supported on structs. Provides a user-supplied error type. It must implement From<UninitializedFieldError>.

• derive = "TYPES" — Supported on structs. Causes the generated Builder to derive the provided list of comma-separated types. Unlike derive_builder, this must be a string. (See derive-deftly#56.)

• struct_attr = "ATTRS", impl_attr = "ATTRS" — Supported on structs. Declares one or more attributes that should be applied verbatim to the builder or to its impl block. These need to include the full attribute syntax, as in struct_attr = "#[must_use]". (This differs from derive_builder in its name and syntax; see derive-deftly#56.)

• field_attr = "ATTRS", setter_attr = "ATTRS" — Supported on fields. Declares one or more attributes that should be applied verbatim to the field in the builder, or to its setter function. These need to include the full attribute syntax, as in field_attr = "#[serde(default)]"). (This differs from derive_builder in its name and syntax; see derive-deftly#56.)

• field(ty) — Supported on fields. Overrides the type of the field as stored in the builder.

• field(build_fn), field(try_build_fn) — Supported on fields. Overrides the code used to generate the field from the field stored in the builder. These options take an expression that must evaluate to a function on &self. The build_fn variant should return the type of the field as it appears in the underlying struct; The try_build_fn should return a Result. (This differs from derive_builder in its name and syntax; see derive-deftly#55.)

• sub_builder, sub_builder(fn_name) — Supported on fields. Behaves as in derive-deftly-fork-arti.

Additional features

We add a Self::builder() method to your original type that returns an empty builder.